When writer and Manhattan society darling, Truman Capote (Toby Jones), reads of the Clutter family murders in Kansas, he is immediately intrigued. He convinces The New Yorker magazine to assign him to write a story. Accompanying him is his friend, Harper Lee (Sandra Bullock), whose book To Kill a Mockingbird is about to be published.
Capote eventually wins over Alvin Dewey (Jeff Daniels), the local officer leading the hunt for the killers. The murderers, Perry Smith (Daniel Craig) and Dick Hickock (Lee Pace) are captured, tried and sentenced to die. Capote visits them in jail, now keen to turn the article into a non-fiction novel, but his association with Perry Smith has unexpected emotional consequences.